1. Field of the Invention
The present invention relates generally to a sensing apparatus and method based on an electromagnetic induction input type, and more particularly, to a sensing apparatus and method of controlling the sensing apparatus that reduce a number of channels used.
2. Description of the Related Art
When entering a specific command into a smartphone or onto a touchscreen, a user can input the specific command or specify a particular icon by placing a part of his/her body or an Electromagnetic Induction (EI) pen on a specific position.
The contact with the part of the user's body can be implemented as a capacitive type. A touchscreen adopting the capacitive type generally includes a condenser component between transparent electrodes. When a user contacts the touchscreen with a part of his/her body, a capacity of the condenser is changed accordingly and the touch can be detected based on the change in capacity.
In this regard, the capacitive type is problematic in that an accurate input is difficult due to a relatively wide contact area that is consumed for the touchscreen contact. In contrast, an EI type requires a small area to receive an input.
For the EI type, a voltage is controlled to be applied to a loop coil arranged on a circuit board to generate an electromagnetic field for propagation to an EI pen. The EI pen may include a condenser and a loop, and may emit the propagated electromagnetic field to have a certain frequency component.
The electromagnetic field emitted by the EI pen may propagate back to the loop coil on the circuit board, thus enabling a determination of which position of the touchscreen the EI pen comes closest.
In the conventional EI type, channels for input and output signals have to be assigned for every loop coil included in the circuit board to apply an electromagnetic filed to the EI pen. Thus, if there are many loop coils on the circuit board, many channels are required and thus, the number of operations required to process signals from the channels may be increased. At the same time, high-performance processors may be required to process the increased number of operations, placing a huge burden on firmware.